You can control the minimum size in bits of the modulus length of the Diffie-Hellman (DH) group that is used to negotiate with connecting peers when using DH cipher suites.
You can specify modulus sizes of 512, 1024, 2048 and 4096 bits.
The default modulus group size is 2048 bits. If you need to work with peers that only support a smaller key size, or you wish to set support to 4096 bits, then you can specify a new value for the DH minimum group size field in either a listener's SSL options (I601) or the MF Directory Server tab.